<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>炫彩边框</title>
  <style>
    .gradient-border {
      border: solid 5px transparent;
      border-radius: 10px;
      background-image: linear-gradient(white, white), 
        linear-gradient(315deg,#833ab4,#fd1d1d 50%,#fcb045);
      background-origin: border-box;
      background-clip: content-box, border-box;
    }
    .box {
      width: 350px;
      height: 100px;
      display: flex;
      align-items: center;
      justify-content: center;
      margin: 100px auto;
    }
  </style>
</head>
<body>
  <div class="box gradient-border">
    炫酷渐变边框
  </div>
</body>
</html>